Investigation of toughening and resistance-curve behavior in hybrid molybdenum disilicide

This paper presents the results of a study of the toughening and resistance -curve behavior in a hybrid molybdenum disilicide (MoSi2) composite that ha s been reinforced with 2 mol% yttria partially stabilized zirconia particle s (TZ-2Y) and niobium layers. Toughening and resistance-curve behavior occu r as a result of the combined effects of crack bridging and transformation toughening. Crack-tip shielding that is due to large-scale crack bridging a nd transformation toughening also is modeled using micromechanics concepts. The models show that the overall crack-tip shielding from transformation t oughening is very limited. However, large-scale bridging by the ductile nio bium layers promotes significant levels of toughening and resistance-curve behavior.